I just had my betta a week or so ago. It got fin rots since 2-3 days. I did a complete 100% water change when I first noticed. then a 50% daily since then.

I added kosher salt (1 teaspoon per gallon) during the water change.
I don't know what to do now.
It's getting worse.
I can see the fin disappearing. Please help!

I had a silk/plastic plant, but i removed it to prevent injury

Housing
What size is your tank? 2.65G
What temperature is your tank? 79-80F
Does your tank have a filter? Yes
Does your tank have an air stone or other type of aeration? No
Is your tank heated? Yes
What tank mates does your betta fish live with? None

Food
What type of food do you feed your betta fish? Nutrafin flakes (does betta food expires?) and pellets
How often do you feed your betta fish? once a day - 2 flakes, 1 pellet

Maintenance
How often do you perform a water change? 2-3days(daily last few days)
What percentage of the water do you change when you perform a water change? 100% once, then 50% from then (100% water change seem to stress him a lot)
What type of additives do you add to the water when you perform a water change? tap conditioner (Fizz Tabs Jungle); and kosher salt (1 teaspoon per gallon)

Water Parameters:
Have you tested your water? If so, what are the following parameters?I only tested ammonia

Ammonia: .25ppm (or 0ppm on the saltwater color card). After changing the water, the reading was the same. I don't know whether to read from freshwater color card or salt because i added salt to the water.
Nitrite: n/a
Nitrate: n/a
pH: n/a
Hardness: n/a
Alkalinity: n/a

Symptoms and Treatment
How has your betta fish's appearance changed? There was no fin rot
How has your betta fish's behavior changed? He was super active, making bubble nest. Today I saw him resting at the bottom of the tank. He never did that before. Even when he sleeps, he sleeps next to the heater, and never on the bottom of the tank. He is still moving, and swimming around though. But his fins are still disintegrating, getting worse everyday! :(
When did you start noticing the symptoms? 3 days ago
Have you started treating your fish? If so, how? Yes, I did daily water change, and added kosher salt (I've read it is the same as aquarium salt)
Does your fish have any history of being ill? no
How old is your fish (approximately)? I have no idea (i think it's an adult)

Wow...normally salt and clean water take care of fin rot...are you sure he's not fin biting? It's hard to tell the difference, but fin rot will have crusty brown gunk at the edges of the fins, whereas biting usually happens quick, like what you've described, and lacks the brown edges.

If it's tail biting, one of mine who does it only seems to do it when he's sick or hurting. (IE, he was sick and I had to medicate him, and he immediately bit his tail again until the end of treatment and new, clean water. I first realized this connection when I purchased him. He was a serious rescue with absolutely no tail, horrible ammonia burns...and he'd bitten his tail down to a nub. Once he started to feel better, the biting stopped.) Other people say boredom can cause it too. If he's bored, you can try getting new tank ornaments, moving them around, lots of plants to swim through, or my favorite, getting a second betta. You can either divide the tank, or you can put two tanks side-by-side. They will flare and swim and interact with each other and keep boredom at bay. All my guys share 20 gals (1 fish per 10 gals) and when one has to be separated, they pout and get depressed while their tankmate is gone.

I hope that might help...If the salt doesn't work, you can try the commercial treatments, but I know that many people on here are NOT fans of the medicines. I've used the Jungle Fungus Cure before (it's not really for fungus, it's an antibiotic and has PPM in it that seems to take care of most bacterial infections) and I believe it's the same stuff as one of the maracyns. Look for the one with nitrofurazone in it, that's the same stuff. It turns the water nasty yellow, but it doesn't seem to be terribly hard on the fish, and might work if the salt and water changes don't.

Sorry for you though, and I hope that your boy is feeling better soon!

Do you have a picture?
As the above person said, the reason why the clean water and salt are not working MIGHT be because he is fin bitting. Are the fins disapearing in a few hours? If so, its probably him snacking on his fins.

I think that the tap conditioner that I used might have been expired. The store had it on special. But I bought a new one today (Slendid betta - complete water conditioner). This one has an expiry date (in 2015). It should be ok, right?

In some places, the fins seem to have become thinner, but at others it’s missing big chunk of fins.

I checked the water. Ammonia is below .25ppm, no nitrite, no nitrate, and ph is 7.5Maybe the bad tap conditioner was making his fins burn, so he started biting it?

If he is snacking on his fins, does that mean he’s hungry? He is always looking for more food, when I’m done feeding him. Should I feed him more?

I will add some decoration, and hiding place so that he can play, and maybe be less bored. :S